Ab-initio study of quantum oscillation in altermagnetic and nonmagnetic phases of RuO$_2$

TL;DR

This study uses first-principles calculations to analyze the Fermi surface of RuO$_2$ in both nonmagnetic and altermagnetic states, aiming to clarify its magnetic ground state through quantum oscillation transport properties.

Contribution

It provides a systematic analysis of RuO$_2$'s Fermi surfaces in different magnetic states to aid experimental identification of its true ground state.

Findings

Fermi surface differences between magnetic states identified

Guidelines for quantum oscillation experiments proposed

Supports experimental determination of RuO$_2$'s magnetic ground state

Abstract

Altermagnet (AM) is a new proposed magnetic state with collinear antiferromagnetic ground state but presents some transport properties that were only believed to exist in ferromagnets or non-collinear antiferromagnets. To have a comprehensive understanding of the transport properties of AMs, especially from the experimental point of view, a promising altermagnetic metal is crucial. In all the proposed altermagnetic metals, RuO$_2$ has a special position, since it is the first proposed AM with the largest spin splitting and several important altermagnetism featured experiments were first performed based on it. However, a very recent report based on sensitive muon-spin measurements suggest a super small local magnetization from Ru, i.e. a nonmagnetic ground state in RuO$_2$. Therefore, a determination of the existence of the altermagnetic ground state is the basic starting point for all the previously altermagnetic transport properties in RuO$_2$. In this work, we propose to identify its magnetic ground state from the Fermi surface (FS) via the electronic transport property of quantum oscillation (QO). We systematically analyzed the FSs of RuO$_2$ in both nonmagnetic and altermagnetic states via first principles calculations. Our work should be helpful for future experiments on QO measurements to confirm its ground state by the interplay between transport measurements and computations.